WASHINGTON — Today's House vote to reverse President Trump's national emergency declaration for his border wall will tell us a lot about how Republicans might break when it comes to special counsel Robert Mueller's ultimate findings.

A test vote on the rule of law? (Can a president bypass Congress if he doesn't get his way?) Check.

A test vote on the separation of powers? (Which branch of government gets to tax and spend money?) You betcha.

A test vote on the number of Republicans willing to break away from Trump? If you're not going to vote against the president on this matter - bypassing Congress' will on build a border wall - you're never going to vote against him.

NBC's Marianna Sotomayor reports that the House vote is expected between 5:15 pm ET and 6:15 pm ET, and the legislation reversing Trump's national emergency declaration has 230 co-sponsors (including one Republican), so it will pass.

Once the legislation clears the House, the Senate has 18 days to vote on it. Guess which GOP senator has come out against Trump's national emergency? Sen. Thom Tillis, R-N.C., who just happens to be up for re-election in 2020.

Michael Cohen plans to make some news

As it turns out,President Trump picked quite the week to be thousands of miles away in Vietnam. In addition to the House vote on his national emergency declaration, former Trump fixer/attorney Michael Cohen is testifying on Capitol Hill - in three different settings:

"Cohen will describe behind the scenes eyewitness, personal observation anecdotes which include lies, racism and cheating as a private businessman when Cohen worked for him for ten years."

"He will also reveal information about Trump's financial statements."

"Cohen will discuss his motives for lying and why he decided to tell the truth publicly for fear of his family and country."

"Did anyone tell him to lie? Cohen will discuss this as well. In Trump world no one talks in declarative sentences."

Replacing Rahm

It's Election Day in Chicago, where a whopping 14 candidates are running to succeed outgoing Mayor Rahm Emanuel. Political observers in the Windy City say an April 2 runoff featuring the Top 2 finishers is virtually guaranteed, since no one is expected to get the 50 percent-plus needed to win outright tonight.

Indeed, breaking into the 20s probably gets you in the runoff.

The top candidates vying to replace Rahm are Cook County Board of Commissioners President Toni Preckwinkle, former Clinton Commerce Secretary and Obama Chief of Staff Bill Daley (whose father and brother served as Chicago mayor), former assistant U.S. attorney Lori Lightfoot (who co-chaired the Chicago Police Accountability Task Force), and Illinois Comptroller Susana Mendoza.

Oh, and get a load of this potential headache: NBC Chicago reports that any of the Top 3 finishers can file for a discovery recount if they're within 5 percentage points of the candidate ahead of them.

In Bernie Sanders' otherwise solid performance at last night's CNN town hall - it helps having run for president before! - this exchange on his tax returns stood out:

CNN: Will you release 10 years of your tax returns? As you know, Elizabeth Warren has decided to do that.

SANDERS: Yes.

CNN: What was the delay? Why haven't you done that so far?

SANDERS: Well, you know, the delay is not -- it'll bore -- our tax returns will bore you to death. It's simply -- nothing special about them. It just was a mechanical issue. We don't have accountants at home. My wife does most of it. And we will get that stuff out.

CNN: So when do you think we'll be able to see your tax returns?

SANDERS: Sooner than later.

CNN: What does that mean?

SANDERS: Soon.

[snip]

CNN: And why didn't you do it the last time around? You were under a lot of pressure to do so.

SANDERS: I wasn't under a lot of pressure. I didn't end up doing it because I didn't win the nomination. If we had won the nomination, we would have done it.

Our takeaway: It doesn't take an accountant to make PDFs of past returns filed to the IRS.

What is he nervous about?

On the 2020 trail today

Joe Biden has a conversation with historian and author Jon Meacham at the University of Delaware.

Data Download: -19 percentage points

That's the margin among independent voters who agree that "The country would be better off if our political and economic systems were more socialist," (37 percent) and those who disagree (56 percent).

According to the poll conducted by the Republican firm Public Opinion Strategies - the GOP half of the NBC/WSJ poll - 45 percent of all registered voters agree that the U.S. would be better off if it were more socialist, including Democrats by a 77 percent-to-19 percent margin ( 58).